Table 2: Performance of model fits using lab spectra of dried samples, evaluated with leave-one-out cross-validation.
pH
Total P (mg/100 g)
Total K (mg/100 g)
Total N (%)
Total N (%)
Total C (%)
Total C (%)
Moisture (%)
Method
PLSR
PLSR
PLSR
PLSR
SMLR
PLSR
SMLR
PLSR
No. of factors
5
2
2
8
2
2
9
2
0.50
0.38
0.79
0.73
0.80
0.79
0.95
0.42
RMSE CV
0.47
29.77
193.92
0.26
0.23
5.17
2.59
10.09
RPD CV
1.42
1.28
2.20
1.93
2.18
2.22
4.43
1.33
RMSE CV: root mean square error of cross-validation, RPD CV: ratio of performance to deviation of cross-validation, PLSR: partial least squares regression, SMLR: stepwise multiple linear regression.